ASTM D3867-2004 Standard Test Methods for Nitrite-Nitrate in Water《水中亚硝酸盐-硝酸盐的标准试验方法》.pdf

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1、Designation: D 3867 04Standard Test Methods forNitrite-Nitrate in Water1This standard is issued under the fixed designation D 3867; the number immediately following the designation indicates the year oforiginal adoption or, in the case of revision, the year of last revision. A number in parentheses

2、indicates the year of last reapproval. Asuperscript epsilon (e) indicates an editorial change since the last revision or reapproval.1. Scope*1.1 These test methods cover the determination of nitritenitrogen, nitrate nitrogen, and combined nitrite-nitrate nitrogenin water and wastewater in the range

3、from 0.05 to 1.0 mg/Lnitrogen. Two test methods2are given as follows:SectionsTest Method AAutomated Cadmium Reduction 9 to 16Test Method BManual Cadmium Reduction 17 to 241.2 These test methods are applicable to surface, saline,waste, and ground waters. It is the users responsibility toensure the va

4、lidity of these test methods for waters of untestedmatrices.1.3 This standard does not purport to address all of thesafety concerns, if any, associated with its use. It is theresponsibility of the user of this standard to establish appro-priate safety and health practices and determine the applica-b

5、ility of regulatory limitations prior to use. For specific hazardstatements, see Note 1 and Note 2.2. Referenced Documents2.1 ASTM Standards:3D 992 Test Method for Nitrate Ion in Water4D 1129 Terminology Relating to WaterD 1141 Practice for the Preparation of Substitute OceanWaterD 1192 Specificatio

6、n for Equipment for Sampling Waterand Steam in Closed Conduits4D 1193 Specification for Reagent WaterD 1254 Test Method for Nitrite Ion in Water4D 2777 Practice for Determination of Precision and Bias ofApplicable Methods of Committee D19 on WaterD 3370 Practices for Sampling Water from Closed Condu

7、itsD 5810 Guide for Spiking Into Aqueous SamplesD 5847 Practice for Writing Quality Control Specificationsfor Standard Test Methods for Water AnalysisE60 Practices for Analysis of Metals, Ores, and RelatedMaterials by Molecular Absorption SpectrometryE 275 Practice for Describing and Measuring Perfo

8、rmanceof Ultraviolet, Visible, and Near Infrared Spectrophotom-eters3. Terminology3.1 Definitions: For definitions of terms used in these testmethods, refer to Terminology D 1129.4. Summary of Test Methods4.1 Total Oxidized Nitrogena filtered sample is passedthrough a column containing copper-coated

9、 cadmium granulesto reduce nitrate ion to nitrite ion. The combined nitrite-nitratenitrogen is determined by diazotizing the total nitrite ion withsulfanilamide and coupling with N-(1-naphthyl)ethylenediamine dihydrochloride to form a highlycolored azo dye that is measured spectrophotometrically.4.2

10、 Nitritethe nitrite ion originally present in the samplecan be determined separately by carrying out the procedure andomitting the cadmium reduction step.4.3 Nitratethe nitrate ion can be calculated as the differ-ence between the combined nitrite-nitrate nitrogen and thenitrite nitrogen.5. Significa

11、nce and Use5.1 Both test methods use identical reagents and sampleprocessing. The only difference between the two methods isthat one test method is automated and the other is manual. Theranges and interferences are identical.5.2 The automated test method is preferred when largenumbers of samples are

12、 to be analyzed. The manual testmethod is used for fewer samples or when automated instru-mentation is not available.5.3 These test methods replace Test Methods D 1254 (Ni-trite) and D 992 (Nitrate). The nitrite test method (Test MethodD 1254) used a reagent that is considered to be a potentialcarci

13、nogen. The nitrate test method (Test Method D 992) has1These test methods are under the jurisdiction of ASTM Committee D19 onWater and are the responsibility of Subcommittee D19.05 on Inorganic Constituentsin Water.Current edition approved July 1, 2004. Published July 2004. Originally approvedin 197

14、9. Last previous edition approved in 1999 as D 3867 99.2Methods similar to these appear in Methods of Chemical Analysis of Water andWastes, 2nd edition, U.S. Environmental Protection Agency.3For referenced ASTM standards, visit the ASTM website, www.astm.org, orcontact ASTM Customer Service at servi

15、ceastm.org. For Annual Book of ASTMStandards volume information, refer to the standards Document Summary page onthe ASTM website.4Withdrawn.1*A Summary of Changes section appears at the end of this standard.Copyright ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428

16、-2959, United States.been shown to have relatively large errors when used inwastewaters and also has greater manipulative difficulties thanthe test method described herein.6. Interferences6.1 Turbid samples must be filtered prior to analysis toeliminate particulate interference. Furthermore, sample

17、turbid-ity results in a buildup on the reduction column that restrictssample flow.6.2 Sample color that absorbs at wavelengths between 520and 540 nm interferes with the absorbance measurements.When color is suspect, analyze a sample blank, omitting theN-(1-naphthyl)ethylenediamine dihydrochloride fr

18、om the colorreagent.6.3 Oil and grease in the sample coat the surface of thecadmium and prevent complete reduction of nitrate to nitrite.This interference is usually removed by filtration prior toanalysis. If filtration is not adequate, the interference can beremoved by extracting the sample with an

19、 n-hexane or a solidphase extraction (SPE) filter.6.4 Certain metal ions, in concentrations above 35 mg/L,may cause interferences. For example, Hg (II) and Cu (II) mayform colored complex ions having absorption bands in theregion of color measurement. Iron and manganese are otherreported examples of

20、 interference.6.5 Excessive amounts of chlorine will deactivate the reduc-ing column. Chlorine might be present in some Type II water.The use of chlorine-containing Type II water will lead to anegative interference because nitrite and chlorine do notnormally coexist. This is of particular importance

21、 when pre-paring standards or spiked samples (Guide D 5810).6.6 In acid samples (pH less than 4.5) nitrate is not reducedin the cadmium column. To overcome this interference, thesample must be neutralized to a pH of between 6 and 8 prior toanalysis.7. Purity of Reagents7.1 Reagent grade chemicals sh

22、all be used in all tests.Unless otherwise indicated, it is intended that all reagents shallconform to the specifications of the Committee on AnalyticalReagents of the American Chemical Society, when suchspecifications are available.5Other grades may be used, pro-vided it is first ascertained that th

23、e reagent is of sufficient highpurity to permit its use without lessening the accuracy of thedetermination.7.2 Purity of WaterUnless otherwise indicated, referencesto water shall be understood to mean reagent water conformingto Specification D 1193, Type I. Other reagent water types maybe used, prov

24、ided it is first ascertained that the water is ofsufficiently high purity to permit its use without adverselyaffecting the bias and precision of these test methods. Type IIwater was specified at the time of round-robin testing of thesetest methods.8. Sampling and Sample Preservation8.1 Collect the s

25、ample in accordance with SpecificationD 1192 and Practices D 3370, as applicable.8.2 When nitrite ion is to be determined separately, analyzeas soon as possible after sampling. Even when sterile bottlesare used, bacteria naturally present in the water may causeconversion of all or part of nitrite io

26、n to other forms such asnitrate or ammonia. Ammonia and natural amines, which arefrequently present in natural waters, may react with nitrites toform nitrogen. If samples are to be stored for 24 h or less,preserve the sample by refrigeration at 4C. If the sample mustbe stored for more than 24 h, pre

27、serve it by the addition of 2mL of chloroform per litre (11.8 and 11.9) in addition torefrigeration at 4C.NOTE 1WARNING: Chloroform is toxic and is a suspected humancarcinogen. Use with adequate ventilation or in a fume hood. Wearprescribed protective equipment. Use of chloroform is discouraged, sin

28、ceits use renders the solution a hazardous waste.NOTE 2CAUTION: The common prescribed use of sulfuric acid ormercury compounds as preservatives is discouraged. Sulfuric acid doesnot necessarily inhibit oxidation and mercury compounds should beavoided to prevent environmental pollution. Mercuric chlo

29、ride is knownto deactivate the column.TEST METHOD AAUTOMATED CADMIUMREDUCTION9. Scope9.1 The applicable range of this test method is from 0.05 to1 mg/L of nitrite or nitrate nitrogen. The range may beextended upward by dilution of an appropriate aliquot. Manyworkers have found that this test method

30、is reliable for nitriteand combined nitrite-nitrate levels to 0.01 mg N/L. However,the precision and bias data presented in this test method areinsufficient to justify application of this test method in the 0.01to 0.05 mg/L-N range.9.2 This test method is applicable to surface, saline, waste,and gro

31、und waters. It is the users responsibility to ensure thevalidity of this test method for waters of untested matrices.10. Apparatus10.1 Automated Analysis System6consisting of:10.1.1 Sampler.10.1.2 Manifold or Analytical Cartridge.10.1.3 Colorimeter equipped with a 15- or 50-mm tubularflow cell and 5

32、40 6 10-nm filters.10.1.4 Recorder or Electronic Data Acquisition Device.10.1.5 Digital Printer (Optional).10.1.6 Continuous Filter (Optional).10.2 Reduction ColumnsChoose the appropriate reduc-tion column for the manifold system. A schematic drawing ofthe manifold system is shown in Fig. 1 and the

33、cartridge systemis shown in Fig. 2.10.2.1 Reduction Column, a glass tube 8 by 50 mm with theends reduced in diameter to permit insertion into the system(see Fig. 1).5“Reagent Chemicals, American Chemical Society Specifications,” AmericanChemical Society, Washington, D.C. For suggestions on the testi

34、ng of reagents notlisted by the American Chemical Society, see Analar Standards for LaboratoryChemicals, BDH Ltd., Poole, Dorset, U.K. and the United States Pharmacopeia andNational Formulary, U.S. Pharmacopeial Convention, Inc. (USPC), Rockville, MD.6The apparatus described is commercially availabl

35、e. ASTM does not undertaketo ensure anyone utilizing an automated analysis system against liability ofinfringement of patent or assume such liability.D 3867 04210.2.2 Reduction Column, a U-shaped glass tubing,350-mm length and 2-mm inside diameter.NOTE 3A pump tube with 0.081-in. (2.1-mm) inside dia

36、meter can beused in place of the 2-mm glass tube.FIG. 1 Nitrite-Nitrate ManifoldFIG. 2 Nitrite-Nitrate CartridgeD 3867 04311. Reagents11.1 Ammonium Chloride Solution (85 g/L)Dissolve 85 gof ammonium chloride (NH4Cl) in water and dilute to 1 L.Add0.5 mL wetting agent.711.2 Cadmium, 40 to 60 mesh, gra

37、nulated.811.3 Color Reagent Add the following to 800 mL ofwater, while stirring constantly: 100 mL of concentratedphosphoric acid (H3PO4), 10 g of sulfanilamide, and 0.5 g ofN-1-(naphthyl)ethylenediamine dihydrochloride. Stir until dis-solved. Add 1 mL of wetting agent,7and dilute to 1 L withwater.

38、This solution is stable for about a month when stored ina brown bottle in a dark cool place.11.4 Copper Sulfate Solution (20 g/L)Dissolve 20 g ofcopper sulfate pentahydrate (CuSO45H2O) in 500 mL ofwater. Dilute to 1 L.11.5 n-Hexane.11.6 Hydrochloric Acid (1 + 1)Slowly add 50 mL ofconcentrated hydroc

39、hloric acid (HCl) to 40 to 45 mL of waterand dilute to 100 mL.11.7 Nitrate Solution, Stock (1.0 mL = 1.0 mg NO3-N)Dry potassium nitrate (KNO3) in an oven at 105C for 24 h.Dissolve 7.218 g in water in a 1-L volumetric flask. Dilute tothe mark with water. This solution is stable for up to 1 monthwith

40、refrigeration. If longer stability is required or refrigerationis not available, add 2 mL of chloroform as a preservative andstore in a dark bottle. This solution is stable for 6 months. (SeeNote 1.)11.8 Nitrate Solution, Standard (1.0 mL = 0.01 mg NO3-N)Dilute 10 mL of stock nitrate solution (11.7)

41、 to 1 L withwater and store in a dark bottle. Prepare fresh as needed.11.9 Nitrite Solution, Stock (1.0 mL = 1.0 mg NO2-N)Place about7gofpotassium nitrite (KNO2) in a tared 125-mLbeaker and dry for about 24 h to a constant weight in adesiccator containing a suitable desiccant. Adjust the weight ofth

42、e dry potassium nitrite to 6.072 g. Add 50 mL of water to thebeaker, stir until dissolved, and transfer quantitatively to a1000-mL volumetric flask. Dilute to the mark with water storein a sterilized bottle under refrigeration. Prepare fresh asneeded.NOTE 4Potassium nitrite is easily oxidized, so us

43、e only fresh bottlesof this reagent.11.10 Nitrite Solution, Standard (1.0 mL = 0.01 mg NO2-N)Dilute 10 mL of stock nitrite solution (11.9) to 1 L withwater. This solution is unstable; prepare fresh as needed.12. Preparation of Reduction Column12.1 Cadmium Granules TreatmentClean and copperizenew or

44、used cadmium granules in the following manner:12.1.1 Clean about 10 g of cadmium granules by washingwith dilute HCl (11.6) and rinsing with water.12.1.2 Swirl the clean cadmium in 100-mL portions ofcopper sulfate solution (11.4) in a beaker for 5 min or until theblue color partially fades. Decant an

45、d repeat with fresh coppersulfate until the first visible brown colloidal precipitate ap-pears.12.1.3 Wash the granules with water at least 10 times toremove all of the precipitated copper.12.2 Filling the Reduction Column:12.2.1 Insert a small plug of glass wool in one end of thecolumn (10.2).12.2.

46、2 Fill the column with water to prevent the entrapmentof air bubbles during the filling operation.12.2.3 Fill the column with copper-cadmium granules, tapto pack the granules, and plug the open end with glass wool.12.3 Installation of Reduction ColumnInstall the copper-cadmium reduction column in th

47、e automatic analyzer system.Purge the system with ammonium chloride solution (11.1)using water in the sample line. Observe the following precau-tions while installing the reduction column:12.3.1 Place the column in the manifold system in anupflow 20 incline to minimize channeling (see Fig. 1).12.3.2

48、 Fill all pump tubes with reagents before inserting thecolumn in the cartridge system to prevent the entrapment of airbubbles.12.4 Reduction Column StorageWhen it is not in use, putthe sample line in water and purge the column with ammoniumchloride solution and water.NOTE 5Do not allow air to enter

49、the column and do not let thecadmium granules become dry. If this occurs, refill the column withfreshly treated cadmium granules.13. Calibration13.1 Using the standard nitrate solution (11.8) preparecalibration standards by pipetting specified volumes of thestandard solution into 100-mL volumetric flasks and diluting tothe mark with water. Table 1 specifies the millilitres of standardsolution required.13.2 Prepare at least one calibration standard from thestandard nitrite solution at the same concentration as one of thenitrate standards to verify the